Most yo-yos typically comprise two disk-shaped side portions that are rigidly connected to each other by some form of axle structure. The side portions are usually of unitary construction and may be made out of plastic, metal or wood. The axle structure is normally secured to the center of both side portions and can be an assembly having multiple parts, or merely be in the form of a dowel or a riveted pin. In many modern yo-yos, a ball bearing unit, or other rotatable member, is secured to, and has at least a portion rotatable on, a center portion of the axle structure.
The axle structure also forms an anchor for one end of a string-type tether. An end-located loop portion of the tether is positioned so that it encircles a center portion of the axle structure. The free end of the tether is usually tied to create a second loop portion that can be placed about one of a user's fingers to thereby temporarily secure the yo-yo to the user's hand.
When one end of the tether is secured to a user's finger and the remainder of the tether is wound about the axle structure, the yo-yo is ready for use. When the yo-yo is released, or thrown, from the user's hand, the yo-yo will begin to rapidly spin as the tether unwinds from about the axle structure and the yo-yo moves away from the user's hand. Once the tether is fully unwound, the yo-yo may “sleep” at the end of the tether, whereby the yo-yo's side portions continue to spin without the tether rewinding on the axle structure. This is enabled by either having the tether's end loop slip on the axle structure, or by having the tether's end loop secured to a freely rotatable member that is secured to, or forms a portion of, the axle structure. Once the yo-yo is sleeping, there are a number of tricks, such as “walk the dog,” that a person can perform with the spinning yo-yo. A sleeping yo-yo is also often used to perform tricks that involve temporarily placing the spinning yo-yo onto a portion of the tether intermediate of the tether's two ends.
When a typical yo-yo is sleeping at the end of the tether and the user wishes to cause the yo-yo to return to his or her hand, the user will make a quick tug/jerk on the yo-yo's tether. This results in a brief tightening of the tether, and is automatically followed by a temporary slackening of the tether. Once the tether goes slack, the tether's twist causes one, or more, portions of the tether located proximate the axle structure to move outwardly and contact a spinning portion of the yo-yo. Once contact has occurred, the tether portion(s) can become snagged on, or otherwise engaged to, the spinning portion of the yo-yo. Continued rotation of the spinning portion of the yo-yo will then cause the tether to wind about the axle structure, resulting in the yo-yo's return to the user's hand.
An extremely important performance characteristic of a yo-yo is its potential sleep time. Since most yo-yo tricks are performed while the yo-yo is sleeping, the longer a yo-yo can be made to sleep, the more time a user will have to complete any particular yo-yo trick. While some tricks can be performed quickly, others require a yo-yo that is capable of sleeping for a relatively long period of time.
To enable the performance of a large variety of tricks, every yo-yo player wants a yo-yo that is capable of sleeping for a long time. However, a long sleep time is extremely difficult to achieve using a basic yo-yo in which the tether slides on the axle structure. The sliding action can create a significant amount of friction that causes the yo-yo to rapidly lose its rotational momentum.
Many modern yo-yos employ a ball bearing that essentially eliminates friction between the tether and the axle structure. However, since friction is not entirely eliminated in ball bearing yo-yos, and yo-yos still experience significant drag due to air resistance, most ball bearing yo-yos will not sleep for longer than about thirty seconds. To achieve even that long a spin time, the user may be required to expend a great deal of effort manipulating the tether to prevent the tether from contacting a spinning portion of the yo-yo. Should the tether contact a spinning portion of the yo-yo, significant friction will be created that can greatly decrease the yo-yo's sleep time.
There is therefore a need in the art for a yo-yo that will readily sleep, and once sleeping, will continue to sleep for an extremely long period of time. In addition, it is desirable to provide a yo-yo that can sleep for an extended period of time that does not require a user to expend significant effort in preventing the tether from contacting a spinning portion of the yo-yo.